Process and product for preventing discoloration of canned foods



Patented Jan. 15,

UNITED STATES PATsNToFFlcl-I.

GEORGE S. BOHABT, OF SAN FRANCISCO, CALIFORNIA, ASSIGIOB TO NATIONAL CAI- Y NERS ASSOCIATION, OF WASHINGTON, DISTRICT OI" COLUIBIA, A CORPORATION OF DELAWARE.

PROCESS PRODUCT FOB YBEVENTIJG DISOOLOEATIOU` OI CANNE!) TUOI-Tl.k

lo Brewingu The invention relates to new and useful improvements in :i process for preventing discoloration of canned foods, and is a continuance in part. of pplicntion Serial No. 96.709, filed by me February 25, 1926.

It is e well known fact that in the processin;v of many canned foods, there are formed sulphur compounds which occasionally react either during processing or subsequent there to, with tin plate metal containers forming dark colored compounds, which are objectionable in appearance.

The present,` invention is directed to a process whereby the formation of such darliy colored compoundsy is prevented.

Through u series of experiments of processing' foods in tin cans, it has been found that if an insoluble metallic compound, such esk zinc oxide or zinc phosphate or a mixture of the two or other insoluble oxides or salts of metals whichdo not form objectionable colored sulphides, is thoroughly incorporated with the ingredients of a protectivecoating of lacquer and homogeneously distributed through said lacquer prior to the application of the lacquer to the tin plate,V so that said compound becomes sy component part of the lacquer, discoloration of the food packed in such cans is avoided.' The inner surface of the body and ends should both cirry the lacquer to inhibit;` sulphide disjloretion ofthe cans or contents.

In carrying outv thel invention, an insoluble metallic com-pound of the character specied is properly mixed with the ingredients forming the lacquer which is to be coated on the metal. The quantity` of zinc oxide, for example, mixed with the lacquer may be varied Within such limits as to produce a lacquer on the tin plate carrying quantities of metallic zinc varying from one-one hundredth of a milligram'to two: milligrams per squareA inch of lacquered surice.

The following mixtures have proved practical in actual use and are detailed below, it being' distinctly understood that this innen tion not limited to the specic mixtures or conditions shown:

1.. (fumer,` 10 pai-tsl and zinc: oxide, 5 parte...

2..` Gunnar, ];8 parts* guita-perche, 4E parts,L and zinc oxide,.11 parts.,

3. Cumul', I8 parte', chicle gum., `4e ports,

I und zinc oxide, 11

Application fled latch 13, im. Serial lo. 94,598.

4. Carnauba wax, 1 part; chicle gum, 1 part and zdinc oxide,1 part.

In maklng u these mixtures, the cumar', chicle gum, an gutta-percha were dissolved in about five parts by weights of carbon tetrachlonde or in some 'cases a little more. A fter complete solution, the zinc oxide was stirred in, and, the mixture was passed through a paint mill twice in ordcrito grind the zinc oxide linely enough to keep it in sus nslon. Carbon tetrachloride was then ad ed in sutlicient amount to reduce the total solids present (including gums, waxes and zinc oxide) to five per cent. The mixture was applied to the metal ofthe cans.

lvhen the insoluble metallic compound is lncorpornted inthe lacquer after the manner above described, il;` becomes permanently embodied in the lacquer and will be held in place o n the inside of the container during processing and subsequently thereto.

v I have found by actual ex rience that the lacquers which can be de ned as baking lacquers stand u the best and give the most.v

satisfactory res ts. It is customary to bake the lacquer with the metallic compound therein on the metal adapted to form the inner surface of the can. Where the cans are .stacked on end, it has also often been proved 1n practice that it is not necessar to apply this lacquer bearing the insolub e metallic compound over the entire inner surface of the :metal container, but if the ends of the container are thus coated, discoloration is avoided. y

Magnesium powder, zinc. dust and slumi num powder, either" sin ly or in combination, can bemixed with t e lacquer and herev been found under "certain conditions to well serve the purpose of preventing discoloration, since these metals prevent forms@ tion of ohjcctionably colored compoundsb The lacquer may `ihnen be 4prepared in the ord-inaqhway and the sheets coated there with. making the entire conte-incr; or ma be used in making the ends or bodies l of the container.

I' claimt: 1.. The process o preventing' the eration of calmed icods comprising pro-viding a. portion of inner surface of the metal forming thei container" for thefood ese coated sheets may be used in A with agholding,y coating having incorporati-ed therewith and; libmogene'ously `'distributed therethrough an insoluble metallic suh-u stance, or 'A substances, l which n do not form objectionablecolored sulphides.

2. The process of preventing the discoloration of canned foods comprising providing .ja `portion of :the f inner surface of the metal forming the container for the food with a holding coatingh'aving incorporated therewith and `homogeneously distributed .i therethrough an" insoluble metallic salt,` or

salts, which do not form objectionable colored sulphides.: f l

` 3Q The process lof preventing the discoloration of canned foods comprising providing" a'portion ofthe inner surface of the metal forming the container for the food with a holding'coating having incorporated therewith i and llhoniogeneously distributed therethrough an insoluble metallic oxide, or

oxides, which do not form objectionable coloration of canned foods comprising providing a port-ionjof the inner surface of the metal forming the containerufor the foodv with a baking lacquer coating having incorporated therewith and homogeneously distributed therethrough an insoluble metallic substance, or substances, which do not form objectionable colored sulphides.

6. The process of preventingthe discoloration of canned foods comprising providing a ortion ofI the inner surface of the metal orming the. container for the food with a baking lacquer coatingA having incorrated therewith and homogeneouslj7 distributed therethrough an insoluble metallic salt, or salts, which do not form objectionable colored sulphides.

7. A can for preventing the discoloration of foods contained therein comprising me'- tallic body and ends, the inner surface of one of which is covered with a holding coating -and an insoluble metallic substance or substances homogeneously distributed'throughout the coating having the'pro erty of forming sulphides which are not o objectionable coloration. v

8. A can comprising metallic bodjT `and. ends, the inner surface of one of which is covered with a baking lac uer throughout which is homogeneously istributed zinc oxide. Y v 9. The process of preventing the discoloration of canned foods comprising providing a port-ion4 of the inner. surface of the metal forming the container forthe food .with a baking lacquer coating having incorporated therewith and homogeneously distributed therethrough an insoluble metallic oxide or oxides, which do not form objectionable colored sulphides.

10il The process of "preventing the 4discoloration ot' canned foods comprising providing a portion'o the inner surface of the metal forming thecontainer for the food withl a baking lacquer coating having incorporated therewith and homogeneously distributed therethrough zinc oxide which does not-form objectionable colored sulphides.

11. A canclosure, one of the surfaces of which `is covered with a packing lacquer' having zinc oxide distributed therethrough.

12. A can closure having applied to onev surface a resinous coating material in which is incorporated an insoluble lmetallic substance Which does not form objectionable colored sulphides.

13. The process of preventing the discoloration of canned foods comprising providing the inner surface or a portion thereof, of the metal forming the container for the food, with alacquer coating having an insoluble metallic compound of such metal or metals forming sulphides which are not dark collored thoroughly incorporated with the in?" gredients and homogeneousl through the lacquer prior to t e application of the lacquer to the surface of the metal, so that said compound is ermanently embodied in the lacquer and hel in place on the inside of the container during processing -and subsequent thereto.

14. The process of preventing the discoloration of canned foods comprising providing the interior surface of the metal forming the container for the food with a holding coating having incorporated therewith and homogeneously distributed therethrough an insoluble metallic substance or substances which do not form objectionable colored sulphides.

15. The process of preventing the discoloration of canned foods comprism providing the inner surface of the metal orming the container for the food with a holdin coating having incorporated therewith and homogeneously distributed therethrough an insoluble metallic salt which does not form objectionable colored sulphides.

16. The process of preventing the discoloration of canned foods comprising providing .the interior surface of the metal forming the container forthe food with a holding coating having incorporated therewith and homogeneously ydistributed therethrough an insoluble metallic oxide which does not form objectionable colored sulphides.

17. The process of preventing discoloration of canned foods comprisin providing the inner surface of the metal orming the distributed tion of foods contained therein comprising metallic body and ends, the inner surfaces of which are covered with a holding coating and an insoluble metallic substance homogeneously distributed throughout the coating having the pro erty of forming sulphides which are not o objectionable coloration.

19. A can comprising metal body and ends, the inner surface of which is covered with a coating throughout which zinc oxide is homogeneously distributed.

20. A product for application to the interior surfaces of cans to prevent discoloration of the food products therein comprising a coating and an insoluble metallic substance homogeneously distributed throughout the coating having the pro erty of forming sulphides which are not o objectionable coloration.

V21. A product for application to the interior surfaces of cans to prevent Vdiscoloration of the food products contained therein comprising a coating and an insoluble melf: lic oxide incorporated therein.

22. A coating product for cans comprising a I lacquer having zinc oxide distributed therethrough.

23. A tinned receptacle having its interior covered with a resinous material in which is incorporated a metallic compound which does not form objectionable colored su1` -phides 24. Ay tinned receptacle for packing food products having its interior coated with a.

.resinous substance having zinc oxide dispersed therethrough.

25., A tinned receptacle for packing food products having its interior coated with a resinous substance in which is incorporated a material which does not form objectionable colored sul hides.

26. A tmned metallic can for packing food products comprising a body and end pieces, the interior of which is coated with l a substance having zinc oxide incorporated therewith.'

In testimony whereof I aflx my signature.

[1.. 8.] GEORGE S. BOHART. 

